1. Field of the Disclosure
The present disclosure relates generally to cavity resonators and, more particularly, to coupling between cavity resonators.
2. Description of the Related Art
A conventional bandpass filter may be constructed of a plurality of resonators that are coupled (or cross-coupled) by coupling elements. The overall transfer function of the filter is created by the combination of the individual transfer functions of the resonators and the coupling elements. For example, a cavity filter may be implemented as a plurality of interconnected cavity resonators. Cavity resonators produce relatively low surface current densities and consequently have relatively high Q-factors, which indicates that the rate of energy loss in the cavity is small relative to the energy stored in the cavity. Other resonators such as transverse electromagnetic (TEM) mode (coaxial) resonators can produce relatively large surface current densities, particularly when used to filter radiofrequency transmissions at powers above hundreds of Watts. Cavity resonator filters are therefore often selected for high-power applications such as filtering radiofrequency transmissions at powers on the order of tens to hundreds of kilowatts for reasons of transmitter output spectrum control.